One of the major advantages of an optical communication system is the capability of transporting very large amounts of data at very high data throughput rates. An optical communication system typically is formed of a fiber optic network having optical fibers through which optical energy is communicated to communicate data between communication endpoints.
Telecommunications carriers (e.g., long distance providers) continually strive to increase the reliability of their communications networks. They do this, in part, by increasing the speed by which they can restore network operation following failure in one or more components of the network. A communications network consists of a collection of transmission links, also known as segments that are interconnected at network nodes. The segments may include transmission lines, fiber optic cables, microwave links, and other such transmission medium. Traffic is transmitted on the network from one endpoint to another endpoint through a current route or “trunk,” which is a network path of segments that interconnect the endpoints. The network nodes may serve a variety of functions such as amplifying the network traffic for transmission down the next segment in the route or establishing an interconnection between two segments connected to the node (i.e., a switch). Each node is located at an installation, and several nodes may be located within a single installation. A regenerator node is a node which is capable of signal regeneration within an optical communication system and can be controlled locally or from a remote computer system to connect or to disconnect segments that are connected to the node. Segments are connected to individual ports of a regenerator node.
As in any communication system, a receiving endpoint must be able to recreate the informational content of the communicated data. The data, when delivered to the communication endpoint, is of sufficient quality that the informational content of the data may still be recovered. Examples of transmission impairments which may result in the quality of the received signal being impacted are signal to noise ratio, chromatic dispersion, polarization mode dispersion and self phase modulation. The degree to which a received signal quality will be reduced by these impairments is dependent on the data being transmitted and the specific characteristics of the converters at each end of the transmission system.
Network outages develop when a discontinuity occurs within the network architecture. A discontinuity within the network may result for reasons such as, a natural disaster, accidental or intentional human intervention, or faulty network components. For example, a segment that is a buried fiber optic cable may fail as a result of being inadvertently severed by someone digging near the buried cable. If one or more of the cables fail, massive disruption of services to a large number of network customers could result. Regardless of the cause of the network outage, however, the communication within the network must be restored as promptly as possible to avoid unnecessary and costly disruptions in communication.
Generally, there are three types of restoration schemes: dedicated restoration, shared restoration, and best effort restoration. In dedicated restoration, the capacity of a protection, or restoration, path is reserved for an individual demand. In shared restoration, the restoration capacity is reserved, but shared across multiple demands. In best effort restoration, no reservation is made and restoration capacity is allocated in real time on an as-available basis. The first two classes of restoration both have guaranteed restoration in the event of a single failure; however, they differ in restoration time, as shared restoration requires real-time path setup.
Generalized Multiprotocol Label Switching (GMPLS) is the next-generation implementation of Multiprotocol Label Switching (MPLS). GMPLS extends the functionality of MPLS to include a wider range of label-switched path (LSP) options for a variety of network devices. GMPLS divides an optical network into two network planes, including a data plane and a control plane. The data plane functions to transmit network data traffic to consist of different types of network switches such as MPLS switches, optical cross connect (OXC) and digital cross connect (DXC). Corresponding to the data plane, the control plane offers control functionalities to control the switches in the data plane.
Signaling component functions to establish, modify, and delete network service connections. For a new network service request, a connection needs to be established between a node pair. Sometimes, an existing connection may be modified in aspects such as bandwidth and traversing route. Also, an existing service may expire after some time. Then the signaling protocol should release the connection and free the resources of the connection. Currently, Resource Reservation Protocol—Traffic Engineering (RSVP-TE) protocol is the most popular signaling protocol for this purpose. Resource Reservation Protocol (RSVP) is a transport layer protocol designed to reserve resources across a communication network. RSVP can be used to request or deliver specific levels of quality of service (QoS) for application data streams or flows. RSVP defines how applications place reservations and how they can relinquish the reserved resources once the need for them has ended. RSVP operation will generally result in resources being reserved in each node along a path. RSVP is not itself a routing protocol and was designed to interoperate with current and future routing protocols. RSVP by itself is rarely deployed in telecommunications networks today but the traffic engineering extension of RSVP, or RSVP-TE, is becoming more widely accepted nowadays in many QoS-oriented networks.
Translucent networks (i.e., with a limited number of regenerators placed in few nodes) offer an efficient bandwidth utilization and guarantee lightpath quality of transmission (QoT). A limited number of opto-electronic regenerators, shared at the nodes, allows to efficiently aggregate traffic and to perform the 3R regeneration required to assure lightpath QoT. Lightpath routing with guaranteed QoT can be performed by an enhanced version of the GMPLS control plane, during both the provisioning and the restoration phases.
To ensure survivability against single link failures, segment protection is used that efficiently shares the regenerators between the working and protection routes. To date, GMPLS-controlled translucent networks are mainly focused on the provisioning phase. The main problem with this issue is that the current GMPLS protocol suite does not encompass regenerator presence. To overcome this issue, in extensions of RSVP-TE protocols are used to disseminate information about regenerator availability during the provisioning phase. However, in dynamic traffic conditions, such as during restoration, regenerator availability information can be inaccurate.
Any discussion of documents, acts or knowledge in this specification is included to explain the context of the invention. It should not be taken as an admission that any of the material forms part of the prior art base or the common general knowledge in the relevant art.